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High Risk Work Licence - Derrick Crane (CD) study materials
High Risk Work Licence - Derrick Crane (CD) study resources

High Risk Work Licence - Derrick Crane (CD) practice questions

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Question 1Work health and safety legislation, duty of care and licence obligations

Under the model Work Health and Safety Act, what is the primary duty of a person conducting a business or undertaking (PCBU) in relation to derrick crane operations?

  1. To provide workers with a copy of the Act and Regulations
  2. To personally inspect the crane every day before work starts
  3. To ensure the health and safety of workers and others so far as is reasonably practicable Correct answer.
  4. To eliminate all hazards on the site before any crane work begins

Explanation

The primary duty of care requires a PCBU to ensure the health and safety of workers and other persons affected by the business, so far as is reasonably practicable. This duty is broad and ongoing and cannot be discharged simply by handing out documents or by one-off inspections.

Question 2Work health and safety legislation, duty of care and licence obligations

A derrick crane is being used to lift a load near a public footpath. Which group of people does the PCBU's duty of care extend to?

  1. Only persons who have signed a site induction
  2. Workers, contractors, visitors and members of the public affected by the work Correct answer.
  3. Only the crane operator and the dogger
  4. Only workers directly employed by the PCBU

Explanation

The duty of care extends to all persons who may be affected by the work, not just employees. This includes contractors, visitors and members of the public such as pedestrians near the footpath. Site induction records do not limit the scope of the duty.

Question 3Work health and safety legislation, duty of care and licence obligations

What is the role of an appointed safety observer during a derrick crane lift?

  1. To watch the load and exclusion zone and warn of danger Correct answer.
  2. To record the lift in the site diary
  3. To inspect the rigging before the lift begins
  4. To operate the crane if the operator needs a break

Explanation

A safety observer is positioned to monitor the load path, the exclusion zone and surrounding hazards, and to alert the operator to danger. The observer does not take over crane controls or perform pre-lift rigging inspections.

Question 4Work health and safety legislation, duty of care and licence obligations

A worker holds a current derrick crane (CD) high risk work licence. What does this licence authorise the holder to do?

  1. Design rigging arrangements for derrick cranes
  2. Supervise all lifting operations on a site
  3. Operate derrick cranes, subject to the duties and site requirements that apply Correct answer.
  4. Operate any crane on any site without further instruction

Explanation

A high risk work licence authorises the holder to perform the specified class of work, here operating derrick cranes. It does not remove the duty to follow site requirements, nor does it confer supervisory or engineering design authority.

Question 5Work health and safety legislation, duty of care and licence obligations

What must a licensed derrick crane operator do if their high risk work licence is lost or damaged?

  1. Apply to the regulator for a replacement licence Correct answer.
  2. Continue operating until the licence expiry date
  3. Ask the site supervisor to write a temporary authority
  4. Rely on a photocopy kept in the site office

Explanation

A lost or damaged licence must be replaced through the relevant regulator, which issues a replacement licence document. Operating without evidence of a current licence can breach licence obligations and site requirements.

Question 6Work health and safety legislation, duty of care and licence obligations

Which statement best describes a worker's duty under work health and safety law while operating a derrick crane?

  1. To purchase their own personal protective equipment
  2. To write the site's emergency plan
  3. To take reasonable care for their own safety and that of others, and to follow instructions Correct answer.
  4. To identify every possible hazard on the site and eliminate it

Explanation

Workers must take reasonable care for their own health and safety and for others affected by their acts or omissions, and must comply with reasonable instructions. Broad hazard elimination and site planning are duties of the PCBU, not the individual worker.

Question 7Work health and safety legislation, duty of care and licence obligations

A derrick crane operator is asked to lift a load that exceeds the crane's rated capacity. What is the correct response under work health and safety obligations?

  1. Refuse the lift and report the overload risk Correct answer.
  2. Proceed if the load is only slightly over the rated capacity
  3. Proceed at reduced speed to lower the load
  4. Proceed if the dogger agrees the load looks stable

Explanation

Exceeding the rated capacity creates an unacceptable risk of structural failure, so the operator must not proceed and should report the issue. Agreement from another worker or slowing the lift does not make an overload safe.

Question 8Work health and safety legislation, duty of care and licence obligations

What is the main purpose of the hierarchy of control when managing risks associated with derrick crane work?

  1. To rank controls so the most reliable, highest-order controls are considered first Correct answer.
  2. To list the cheapest control measures available
  3. To assign blame after an incident
  4. To satisfy insurers rather than regulators

Explanation

The hierarchy of control ranks options from eliminating the hazard through substitution and engineering controls to administrative controls and PPE. Higher-order controls are considered first because they are generally more reliable at reducing risk.

Question 9Work health and safety legislation, duty of care and licence obligations

A PCBU engages a subcontractor to erect a derrick crane. How do the PCBU's duties interact with the subcontractor's duties?

  1. The PCBU and subcontractor each have duties, and duties cannot be transferred away Correct answer.
  2. Only the subcontractor owes any duty for the erection work
  3. The PCBU is liable only if the subcontractor becomes insolvent
  4. The PCBU's duty ends once the subcontractor is engaged

Explanation

Duties under work health and safety law are held by each duty holder and cannot be contracted out or transferred. A PCBU engaging a subcontractor must still consult, coordinate and manage risks so far as reasonably practicable.

Question 10Work health and safety legislation, duty of care and licence obligations

Before a derrick crane lift, what does the duty to consult with workers require?

  1. That workers be given information and the opportunity to express views on safety matters affecting them Correct answer.
  2. That workers approve the crane's purchase price
  3. That only management decide and inform workers afterwards
  4. That workers vote on whether the lift should proceed

Explanation

Consultation requires sharing relevant information, giving workers a reasonable opportunity to express views, and taking those views into account. It is not a voting process and does not transfer decision-making authority to workers.

Question 11Work health and safety legislation, duty of care and licence obligations

A derrick crane operator notices a defect in the crane's slewing brake. What is the appropriate action?

  1. Continue working and note the defect at the end of the shift
  2. Reduce the load by half and keep operating
  3. Ask a co-worker to watch the brake while lifting
  4. Stop using the crane and report the defect for assessment and repair Correct answer.

Explanation

A defective brake affects safe control of the load, so the equipment should be taken out of service and reported so it can be assessed and repaired. Working around a known safety defect is not an acceptable control.

Question 12Work health and safety legislation, duty of care and licence obligations

What does the term 'reasonably practicable' require a PCBU to weigh when deciding on controls for derrick crane work?

  1. Only whether the control was used on previous projects
  2. Likelihood and severity of harm against the cost, effort and availability of controls Correct answer.
  3. The preferences of the crane manufacturer alone
  4. Only the cost of the control measure

Explanation

Reasonably practicable involves weighing the likelihood and degree of harm against what is known about the hazard and the cost, effort and availability of ways to eliminate or reduce it. Cost alone does not determine the outcome, and the assessment is not limited to past practice.

Question 13Work health and safety legislation, duty of care and licence obligations

A derrick crane is to be used for the first time on a site. Which document should define the safe system of work for the lift?

  1. A safe work method statement or lift plan prepared for the task Correct answer.
  2. The manufacturer's sales brochure
  3. The crane operator's licence card
  4. The site's visitor sign-in register

Explanation

A task-specific lift plan or safe work method statement sets out the hazards, controls, responsibilities and sequence for the lift. Licence cards and registers are administrative records and do not describe the safe system of work.

Question 14Work health and safety legislation, duty of care and licence obligations

What is the operator's obligation regarding pre-start checks of a derrick crane before the first lift of the day?

  1. Carry out the required checks and record or report any defects found Correct answer.
  2. Skip checks if the crane was used the previous day
  3. Perform checks only after the first lift is completed
  4. Delegate checks to any nearby worker regardless of competence

Explanation

Pre-start checks are part of the operator's routine duties and must be completed before use, with defects recorded or reported. Previous use does not remove the need for checks, and checks must be done by a competent person before lifting.

Question 15Work health and safety legislation, duty of care and licence obligations

An operator's high risk work licence has expired. What is the operator's position under work health and safety law?

  1. They may operate if supervised by a licensed colleague
  2. They must not perform licensed derrick crane work until the licence is renewed Correct answer.
  3. They may keep operating while a renewal is being processed
  4. They may operate only for loads under one tonne

Explanation

Performing high risk work without a current licence is unlawful, and a pending renewal does not authorise continued work. Supervision by another licensed person does not cure the operator's lack of a licence.

Question 16Work health and safety legislation, duty of care and licence obligations

A derrick crane lift is planned near overhead powerlines. Which duty holder obligation applies?

  1. The PCBU must identify the hazard and implement controls such as exclusion zones or de-energising Correct answer.
  2. The operator alone must manage the electrical risk
  3. No action is needed if the crane is not metal
  4. The electricity supplier alone is responsible for crane clearances

Explanation

The PCBU must identify electrical hazards and apply controls, such as maintaining safe approach distances, isolating supply or using spotters, before work begins. Responsibility is not shifted to the operator alone or to the electricity supplier.

Question 17Work health and safety legislation, duty of care and licence obligations

A derrick crane has been modified by welding an additional bracket to the boom. How should the PCBU treat this modification?

  1. As a matter for the operator to monitor during lifts
  2. As a routine repair needing no further assessment
  3. As acceptable if the weld looks strong
  4. As an alteration that must be assessed and approved by a competent person before use Correct answer.

Explanation

Alterations to plant can affect structural integrity and must be assessed and approved by a competent person, with records updated, before the crane is returned to service. Visual appearance is not a substitute for engineering assessment.

Question 18Work health and safety legislation, duty of care and licence obligations

Two PCBUs share a site where a derrick crane will operate. What does the law require of them in relation to their overlapping duties?

  1. They must merge into a single legal entity
  2. Each must consult, cooperate and coordinate activities with the other so far as reasonably practicable Correct answer.
  3. The principal contractor must assume all duties of the other PCBU
  4. Each may ignore the other's activities if separate contracts exist

Explanation

Where more than one duty holder has the same duty, each must discharge it so far as reasonably practicable and consult, cooperate and coordinate activities with the others. Duties are not absorbed by a principal contractor, and separate contracts do not remove them.

Question 19Work health and safety legislation, duty of care and licence obligations

An incident occurs in which a derrick crane load drops and narrowly misses a worker. What notification obligation applies to the PCBU?

  1. Record it in the site diary and take no further action
  2. Notify the regulator of the dangerous incident as required by the regulations Correct answer.
  3. Notify only the crane manufacturer
  4. No notification is needed because no one was injured

Explanation

A dangerous incident, such as a load drop that could have caused serious harm, is notifiable to the regulator even without injury. Internal record keeping and manufacturer notification do not replace the regulatory notification duty.

Question 20Work health and safety legislation, duty of care and licence obligations

A licensed operator is directed by a site manager to make a lift that the operator believes is unsafe because the outrigger pads are sinking. What is the operator's best course of action?

  1. Make the lift but keep the load low and move quickly
  2. Obey the direction because the manager holds authority over the site
  3. Stop the lift, explain the hazard, and have the ground conditions assessed and corrected Correct answer.
  4. Ask the dogger to stand on the outrigger to stabilise it

Explanation

The operator has a duty to stop unsafe work and must not proceed where ground conditions threaten stability. The hazard should be reported and corrected, such as by proper pad design or ground assessment, before lifting resumes.

Question 21Hazard identification, risk assessment and control in crane operations

Before a derrick crane lifts a load from a wharf, which factor most directly determines the crane's safe working load for that particular lift?

  1. The colour of the load being lifted
  2. The number of workers standing nearby
  3. The time of day the lift is performed
  4. The radius of the boom at the lift position Correct answer.

Explanation

A derrick crane's capacity decreases as the working radius increases, so the safe working load must be read from the load chart for the actual radius and configuration. Other site conditions matter for planning but do not set the rated capacity.

Question 22Hazard identification, risk assessment and control in crane operations

A load chart for a derrick crane shows a much lower capacity when the boom is at a low angle. What is the main reason for this reduction?

  1. The winch brake is less effective at low angles
  2. The load radius increases, raising the overturning moment Correct answer.
  3. The rope speed increases at low boom angles
  4. The hook block becomes heavier at low angles

Explanation

Lowering the boom angle increases the horizontal distance from the crane's centre of rotation to the load, which increases the overturning moment on the mast and foundation. The chart therefore permits less load at larger radii.

Question 23Hazard identification, risk assessment and control in crane operations

During planning, a rigger notices the derrick crane's outrigger pad is sitting on recently filled ground. What is the most appropriate control?

  1. Spread the load over a larger area with engineered matting and verify bearing capacity Correct answer.
  2. Proceed but lift at half speed
  3. Ask the dogman to stand closer and watch the pad
  4. Add extra counterweight to the crane

Explanation

Ground bearing capacity must be assessed and, where it is inadequate, improved by spreading the load over a larger area with suitable mats or a designed pad. This prevents settlement that could destabilise the crane.

Question 24Hazard identification, risk assessment and control in crane operations

Which document should be consulted to confirm the maximum wind speed at which a derrick crane may continue operating?

  1. The toolbox talk attendance sheet
  2. The delivery docket for the last load
  3. The site's visitor sign-in register
  4. The crane manufacturer's operating manual and load chart notes Correct answer.

Explanation

The manufacturer specifies the maximum permissible wind speed for safe operation, often varying with boom length and load sail area. Site procedures should reflect these limits and require monitoring.

Question 25Hazard identification, risk assessment and control in crane operations

A derrick crane is being used to lift large steel plates with a high surface area. Why does this increase risk compared with lifting a compact load of the same mass?

  1. The large sail area catches wind, increasing side load and swing Correct answer.
  2. Steel plates cannot be slung with slings
  3. The crane's winch cannot lift flat objects
  4. The plates are always heavier than they appear

Explanation

A large surface area acts like a sail, so wind creates significant side forces and uncontrolled swing that can overload the boom or mast. Loads with high sail area need lower wind limits and tag line control.

Question 26Hazard identification, risk assessment and control in crane operations

What is the primary purpose of a lift study or lift plan for a complex derrick crane operation?

  1. To replace the need for a competent dogman
  2. To identify hazards, sequence the lift and specify controls before work starts Correct answer.
  3. To record the crane operator's daily hours
  4. To satisfy the client's invoicing requirements

Explanation

A lift plan systematically identifies hazards, defines the lift sequence, selects equipment and states controls and responsibilities. It is a planning tool that must be communicated to the crew before the lift.

Question 27Hazard identification, risk assessment and control in crane operations

A derrick crane will lift a load that must be rotated into position over a live traffic lane. Which control best manages the risk to the public?

  1. Close or divert the lane and use a planned exclusion zone for the lift Correct answer.
  2. Ask the crane operator to lift more quickly to reduce exposure time
  3. Schedule the lift during a quiet period without any other controls
  4. Rely on vehicle drivers to stop when they see the crane

Explanation

Eliminating or separating the public from the hazard is the most reliable control, so closing or diverting the traffic lane during the lift is preferred. Physical separation and a planned exclusion zone protect people who cannot control the hazard themselves.

Question 28Hazard identification, risk assessment and control in crane operations

Why must a derrick crane's slew or swing area be barricaded during operation?

  1. To keep the crane's hydraulic oil warm
  2. To reduce noise from the winch
  3. To prevent people being struck or crushed by the rotating superstructure and load Correct answer.
  4. To stop birds landing on the boom

Explanation

The rotating superstructure and suspended load create a crush and strike hazard in the swing zone. Barricading and signage keep people out of the area where they could be trapped against fixed objects.

Question 29Hazard identification, risk assessment and control in crane operations

A dogman notices the load begins to drift sideways as it is lifted clear of the ground. What is the most appropriate immediate action?

  1. Signal the operator to stop and lower the load for reassessment Correct answer.
  2. Continue the lift and correct the drift at height
  3. Ignore the drift because the load is still within capacity
  4. Increase the hoist speed to clear the obstruction

Explanation

Unexpected sideways movement indicates an unbalanced load, snagged sling or wind effect, any of which can cause loss of control. Stopping and lowering the load allows the cause to be found and corrected before continuing.

Question 30Hazard identification, risk assessment and control in crane operations

Which of the following is the best example of a higher-order control for the hazard of a suspended load passing over workers?

  1. Issuing high-visibility vests to all workers
  2. Rerouting the lift path so the load never passes over occupied areas Correct answer.
  3. Placing a warning sign at the site gate
  4. Briefing workers to look up when the crane moves

Explanation

The hierarchy of control ranks eliminating exposure above administrative measures, so designing the lift path to avoid occupied areas is the strongest control. Briefings, signs and PPE rely on human behaviour and do not remove the hazard.

Question 31Hazard identification, risk assessment and control in crane operations

During a pre-lift inspection, a rigger finds a wire rope sling with broken outer wires and a kink. What should happen?

  1. Cover the damaged section with tape and proceed
  2. Use the sling for light loads only
  3. Straighten the kink by hand and continue
  4. Tag the sling out of service and replace it before the lift Correct answer.

Explanation

Broken wires and kinks reduce a sling's strength and are grounds for removal from service. Damaged lifting gear must be tagged out and replaced so it cannot be used inadvertently.

Question 32Hazard identification, risk assessment and control in crane operations

A derrick crane is set up near an excavation with a vertical cut face. What geotechnical concern is most relevant to the crane's stability?

  1. The risk of the excavation edge collapsing and undermining the crane foundation Correct answer.
  2. The depth of the crane's paint finish
  3. The colour of the excavated soil
  4. The number of spoil trucks waiting

Explanation

Loads imposed by the crane near an excavation can cause the cut face to fail, particularly where there is no setback or shoring. The crane must be positioned outside a defined zone of influence based on geotechnical advice.

Question 33Hazard identification, risk assessment and control in crane operations

What is the main hazard created by lifting a load that has absorbed rainwater and become much heavier than expected?

  1. The load may become magnetic
  2. The slings may become electrically charged
  3. The crane's horn may fail to operate
  4. The actual load may exceed the crane's rated capacity for the radius Correct answer.

Explanation

Water absorption can substantially increase mass, and if the actual load exceeds the rated capacity for the working radius the crane or rigging can fail. Loads should be weighed or their mass confirmed before lifting.

Question 34Hazard identification, risk assessment and control in crane operations

Why is a tag line used when lifting a large, awkwardly shaped load with a derrick crane?

  1. To provide an electrical earth for the crane
  2. To measure the wind speed at the load
  3. To increase the crane's lifting capacity
  4. To control rotation and swing of the load from a safe distance Correct answer.

Explanation

A tag line lets a person guide the load's orientation from outside the danger zone, reducing uncontrolled rotation and swing. It must be used from a position where the person cannot be struck or pulled into the load path.

Question 35Hazard identification, risk assessment and control in crane operations

A crane operator reports that the derrick crane's load moment indicator is showing intermittent faults. What is the correct response?

  1. Stop the lift until the fault is diagnosed and repaired by a competent person Correct answer.
  2. Reduce the load by ten percent and keep working
  3. Continue operating and rely on the operator's judgement
  4. Disconnect the indicator so it stops alarming

Explanation

A load moment indicator is a critical safety device that warns of overload and must be functioning correctly before work continues. Intermittent faults require the crane to be taken out of service until a competent person repairs and verifies it.

Question 36Hazard identification, risk assessment and control in crane operations

What is the key risk when two cranes, including a derrick crane, are used to lift a single load without a coordinated plan?

  1. The load becomes lighter during the lift
  2. Uneven load sharing can overload one crane and cause loss of control Correct answer.
  3. The slings will automatically lengthen
  4. The crane engines will overheat

Explanation

Tandem lifts require a documented plan because load sharing changes as the load moves and one crane can become overloaded. Without coordination, the load can shift suddenly and cause structural failure or uncontrolled movement.

Question 37Hazard identification, risk assessment and control in crane operations

Which environmental condition should trigger an immediate review of a derrick crane lift, even if the load is within capacity?

  1. The presence of clouds in the sky
  2. A sudden onset of strong gusty wind Correct answer.
  3. A slight drop in ambient temperature
  4. An increase in background traffic noise

Explanation

Gusty wind increases side loading and can exceed the manufacturer's wind limit, so the lift must be reassessed or stopped. Wind speed should be monitored at the crane, not just at ground level.

Question 38Hazard identification, risk assessment and control in crane operations

A load must be lifted over a fragile roof that workers are repairing. Which combination of controls best manages the risk?

  1. Place a sign on the roof warning of falling loads
  2. Schedule the lift for lunchtime and rely on workers staying alert
  3. Ask the crane operator to swing the load quickly over the roof
  4. Relocate the workers off the roof during the lift and plan a route that avoids the fragile area Correct answer.

Explanation

Removing people from beneath the load and routing the lift away from the fragile area eliminates exposure rather than relying on behaviour. Fragile roofs can also fail under impact, so avoiding them protects both workers and the structure.

Question 39Hazard identification, risk assessment and control in crane operations

Why should the area beneath a derrick crane's load be kept clear even when the load is only lifted a short distance?

  1. Because the hook must be stored on the ground
  2. Because a load or rigging failure can drop the load without warning Correct answer.
  3. Because short lifts are always more dangerous than long lifts
  4. Because the crane cannot lift loads above waist height

Explanation

Any suspended load can fall if a sling, shackle or crane component fails, and the distance lifted does not remove that consequence. Keeping the area beneath the load clear ensures nobody is injured by a sudden drop.

Question 40Hazard identification, risk assessment and control in crane operations

A site introduces a new crane crew unfamiliar with the derrick crane's controls. Which control most directly reduces the risk of an incident during the first lifts?

  1. Providing a written manual without any discussion
  2. Allowing the crew to learn by trial and error on live lifts
  3. Increasing the number of spotters on the ground
  4. Supervised familiarisation and verification of competency before independent operation Correct answer.

Explanation

Competency must be verified for the specific crane type, and supervised familiarisation allows skills to be checked before independent work. This directly addresses the human error risk from inexperience.

Question 41Derrick crane types, components, configuration and stability principles

In a derrick crane, which component takes the main compressive load from the mast down into the supporting structure?

  1. The slewing ring gear
  2. The counterweight box
  3. The boom luffing rope
  4. The mast or king post Correct answer.

Explanation

The mast (king post) is the vertical member that carries the crane's vertical and overturning loads into the base or building structure. Ropes and gears transmit motion rather than acting as the primary compression path.

Question 42Derrick crane types, components, configuration and stability principles

A derrick crane is described as 'stiff-legged'. What distinguishes this configuration?

  1. The mast is fixed to the ground with no guy ropes at all
  2. The boom is supported by two rigid struts instead of a single mast Correct answer.
  3. The crane is mounted on a crawler undercarriage
  4. The boom is telescopic and extends hydraulically

Explanation

A stiff-legged derrick uses two inclined rigid legs (struts) anchored to the structure in place of a central mast, giving greater headroom and stiffness. The legs transmit load in compression rather than relying on a vertical post.

Question 43Derrick crane types, components, configuration and stability principles

Why must the guy ropes of a guyed derrick be arranged symmetrically with roughly equal tension?

  1. To reduce the rope diameter required for the hoist line
  2. To ensure the counterweight can be removed during operation
  3. To keep the resultant of the guy forces acting through the mast axis and prevent unbalanced overturning moment Correct answer.
  4. To allow the boom to slew faster around the mast

Explanation

Guy ropes resist the overturning moment generated by the load and boom. If tensions are unequal, the horizontal resultant shifts and imposes an unintended bending and overturning moment on the mast and anchors.

Question 44Derrick crane types, components, configuration and stability principles

What is the primary function of the derrick crane's counterweight or ballast?

  1. To offset the load moment and reduce the net overturning moment on the mast Correct answer.
  2. To lubricate the slewing bearing during rotation
  3. To increase the maximum hoist speed
  4. To provide a mounting point for the operator's cab

Explanation

Ballast or counterweight creates a moment opposite to the load moment, reducing the net overturning moment that the mast, guys and foundation must resist. It improves stability but does not change the rated capacity chart directly.

Question 45Derrick crane types, components, configuration and stability principles

Which term describes the derrick crane's ability to resist tipping about the base or anchor points under load?

  1. Stability Correct answer.
  2. Slew rate
  3. Reeving ratio
  4. Rigging efficiency

Explanation

Stability is the capacity of the crane to resist overturning moments about its support points. It depends on the load moment, counterweight moment, guy tensions and the geometry of the base.

Question 46Derrick crane types, components, configuration and stability principles

What is the purpose of the boom foot or boom pivot pin on a derrick crane?

  1. To connect the hoist rope directly to the load hook
  2. To lock the boom at a single fixed radius permanently
  3. To allow the boom to be raised and lowered about a fixed hinge point Correct answer.
  4. To carry the slewing motor and gearbox

Explanation

The boom foot pin forms the hinge about which luffing occurs, transferring boom loads into the mast or base structure. It must be free to rotate for luffing but restrained against axial movement.

Question 47Derrick crane types, components, configuration and stability principles

A derrick crane's load chart shows a lower capacity at maximum radius. What is the main reason?

  1. The counterweight becomes lighter at long radius
  2. The load moment increases with radius, so the allowable load must decrease to keep the overturning moment within limits Correct answer.
  3. The hoist rope becomes shorter as the boom is lowered
  4. The slewing motor loses power at long radius

Explanation

Load moment is the product of load and radius. As radius increases, the same load produces a larger overturning moment, so the chart reduces allowable load to stay within the crane's stability and structural limits.

Question 48Derrick crane types, components, configuration and stability principles

Which statement best describes the base or foundation requirement for a fixed derrick crane?

  1. It must be designed to resist the maximum vertical load and overturning moment imposed by the crane Correct answer.
  2. It only needs to support the weight of the mast and nothing else
  3. It only resists the hoist rope tension during lifting
  4. It can be any flat concrete surface regardless of load rating

Explanation

The foundation must transfer both the vertical load and the overturning moment generated by the load and boom into the ground. Anchor bolts, ballast and concrete strength must match the crane manufacturer's specification.

Question 49Derrick crane types, components, configuration and stability principles

A derrick crane is being set up on a roof. Which factor most directly reduces its stability margin?

  1. The roof structure deflecting under the anchor loads Correct answer.
  2. The number of spare sheaves stored in the site shed
  3. The colour of the crane's paint finish
  4. The length of the operator's shift

Explanation

Deflection or movement of the supporting structure allows the mast to tilt, increasing eccentricity and overturning moment. Anchor points must therefore be tied to a structure verified as capable of resisting the design loads.

Question 50Derrick crane types, components, configuration and stability principles

During a lift, the boom of a guyed derrick is luffed down to a lower angle. What happens to the load moment about the mast base for the same suspended load?

  1. It increases because the horizontal radius increases Correct answer.
  2. It decreases because the boom is closer to horizontal
  3. It stays exactly the same at all boom angles
  4. It becomes zero when the boom passes 45 degrees

Explanation

Load moment equals load multiplied by horizontal radius. Lowering the boom increases the horizontal distance from the mast to the load, so the moment rises and the crane approaches its stability limit.